After numerous reports of UFOs patrolling the interplanetary space near Earth, the AAB Gamma was launched by the Japanese government to look for them. Once in space, the AAB Gamma searched the areas where sightings had been reported, and eventually discovered a single UFO. The UFO began coating the AAB Gamma in an unusual substance that looked like spores, before swiftly fleeing. With its mission considered complete, the AAB Gamma was ordered to return to Earth. Although most of the spores burnt off when the AAB Gamma re-entered the atmosphere, one remained, and developed into the space kaiju Guilala.
- The AAB Gamma is referenced in The Monster X Strikes Back: Attack the G8 Summit by the similarly-named AAC-Beta, a space probe launched by China. Just like the AAB Gamma, the AAC-Beta returned to Earth carrying Guilala in his spore form.